Lighting Device Having a 3D Scattering Element and Optical Extractor With Convex Output Surface

ABSTRACT

A lighting device includes (1) one or more solid-state lighting (SSL) devices, (2) a thick, for example prism- or cylinder- or spherical- or dome-shaped scattering element, and (3) an optical extractor with a convex output surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 15/529,458, filed on May 24, 2017, which is a U.S. National Phaseapplication of International Application No. PCT/US2015/062749, filed onNov. 25, 2015, which claims benefit under 35 U.S.C. § 119(e)(1) of U.S.Provisional Application No. 62/084,358, filed on Nov. 25, 2014, whichare incorporated by reference herein.

TECHNICAL FIELD

The present technology pertains in general to lighting devices includingsolid-state lighting (SSL) devices and in particular to lighting devicesincluding thick, for example prism- or cylinder- or spherical- ordome-shaped scattering elements and an optical extractor with a convexoutput surface.

BACKGROUND

The development of lighting devices has focused in many ways on how toextract as much light as possible into the ambient and while doing soprovide at least some directionality of propagation to the light to makeit useful for application in space illumination, indication, displayand/or other lighting applications. Such aspects apply to all types ofSSL and non-SSL lighting devices and generally manifest themselves inthe design of the optical subsystem. These requirements are particularlyrelevant when light is generated within optically dense material.Efficient utilization of high brightness light that originates fromquasi-point sources and controlling respective glare provides a numberof challenges for optical subsystem design. These and other aspects havebecome increasingly important in the configuration of light-emittingdiodes (LEDs), LED-based lighting devices and other SSL devices.

SSL devices in particular are finding rapid adoption in large portionsof illumination applications due to their low power consumption, highluminous efficacy and longevity in comparison to incandescent andfluorescent light sources. SSL devices have been developed that cangenerate quality white light via down-conversion of short wavelengthpump light, including ultraviolet, blue or other light provided bycorresponding LEDs, via a suitable luminescent material (also referredto as a phosphor). Such devices may be referred to as phosphor-basedLEDs (PLEDs). Although subject to losses in efficacy due tolight-conversion, various aspects of PLEDs promise reduced complexity,better cost efficiency and durability of PLED-based luminaires incomparison to luminaires that generate white light from light emitted byvarious combinations of LEDs that directly generate red, green, blue,amber and/or other colors of light, for example.

While new types of phosphors are being actively investigated anddeveloped, configuration of PLED-based lighting devices and/orluminaires, however, provides further challenges due to the propertiesof available luminescent materials. Challenges include light-energylosses from photon conversion, generally referred to as Stokes loss orStokes shift, self-heating from Stokes loss, dependence of photonconversion properties on operating temperature, degradation due topermanent changes of the chemical and physical composition of phosphorsin effect of overheating or other damage, dependence of the conversionproperties on intensity of light, propagation of light in undesireddirections in effect of the random emission of converted light that isemitted from the phosphor, undesired chemical properties of phosphors,and controlled deposition of phosphors in lighting devices, for example.

Therefore there is a need for a lighting device that overcomes at leastone of the deficiencies of the state-of-the art.

SUMMARY

In general, innovative aspects of the technologies described herein canbe implemented in a lighting device that includes one or more of thefollowing aspects:

In a first aspect, a lighting device includes one or more light-emittingelements (LEE) configured to provide pump light, and a scatteringelement including a matrix of phosphor embedded in dielectric material.The phosphor is configured to absorb at least a portion of the pumplight and to emit converted light with converted light wavelengthslonger than pump light wavelengths. The dielectric material istransparent to the pump light and the converted light. The scatteringelement forms an input interface with the LEEs, such that the pump lightemitted by the LEEs is input into the scattering element through theinput interface. The input interface has a first dimension. Thescattering element has a second dimension orthogonal to and 1-10 timeslarger than the first dimension. Additionally, the lighting deviceincludes an optical extractor forming an extraction interface with thescattering element, such that mixed light from the scattering element isinput into the optical extractor through the extraction interface. Anoutput surface of the optical extractor is arranged and shaped relativeto the extraction interface such that the mixed light received by theoptical extractor through the extraction interface impinges on theoutput surface at incident angles smaller than or equal to the criticalangle θ_(C)=arcsin(n_(E)/n_(O)), where n_(E) is a refractive index ofthe optical extractor, and n_(O) is a refraction index of an environmentsurrounding the optical extractor.

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. In someimplementations, the extraction interface has a third dimension beingalong, and 3-30 times larger than, the first dimension. In someimplementations, the extraction interface is shaped as a portion of asphere, and the second dimension of the scattering element correspondsto a radius of the sphere.

In some implementations, the phosphor can be uniformly distributedwithin the dielectric material. In some implementations, the dielectricmaterial of the matrix can be plastic or glass. In some implementations,the one or more LEEs can include one or more LED dies. In someimplementations, the one or more LEEs can include one or more LEDpackages. In some implementations, the mixed light can include a portionof the converted light and a portion of the pump light that isunconverted by the phosphor. In any of the foregoing implementations,the lighting device further can include a reflector extending from theinput interface to a boundary of the extraction interface.

In some implementations, the optical extractor can be arranged andshaped relative to the extraction interface such that the incidentangles at which the mixed light impinges on the extraction interface arelarger than or equal to the Brewster angle θ_(B)=arctan(n_(E)/n_(O)). Insome implementations, the optical extractor can be arranged and shapedrelative to the extraction interface such that the incident angles atwhich the mixed light impinges on the extraction interface are smallerthan the Brewster angle θ_(B)=arctan(n_(E)/n_(O)).

In a second aspect, a lighting device includes one or morelight-emitting diodes (LEDs) configured to provide pump light, and ascattering element including a matrix of phosphor embedded in dielectricmaterial. The phosphor is configured to absorb at least a portion of thepump light and to emit converted light with converted light wavelengthslonger than pump light wavelengths. The dielectric material istransparent to the pump light and the converted light. The scatteringelement forms an input interface with the LEDs, such that the pump lightemitted by the LEDs is input into the scattering element through theinput interface. The input interface has a first dimension. Thescattering element has a second dimension orthogonal to and 1-10 timeslarger than the first dimension. Additionally, the lighting deviceincludes an optical extractor forming an extraction interface with thescattering element, such that mixed light from the scattering element isinput into the optical extractor through the extraction interface. Anoutput surface of the optical extractor has a radius R_(O) thatsatisfies the condition

R _(O) ≥R _(E)(n _(E) /n _(O)),

where R_(E) is a radius of a notional sphere that inscribes theextraction interface, and wherein n_(E) is a refractive index of theoptical extractor and n_(O) is a refraction index of an environmentsurrounding the optical extractor.

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. In someimplementations, the scattering element can be shaped as a sphericaldome of the notional sphere with the radius R_(E), such that the seconddimension of the scattering element corresponds to the radius R_(E), andthe optical extractor can be shaped as a spherical shell having an innerradius that corresponds to the radius R_(E). In some implementations,the scattering element can be shaped as a cylinder having a height equalto the second dimension, and a base diameter 2R_(E) that is along, and3-30 times larger than, the first dimension; and the optical extractorcan be shaped as a spherical dome with the radius R_(O).

In some implementations, the radius R_(O) can satisfy the condition

R _(O) =R _(E)(n _(E) /n _(O)).

In some implementations, the radius R_(O) can satisfy the condition

R _(E)(n _(E) /n _(O))<R _(O) <R _(E)√[1+(n _(E) /n _(O))²].

In some cases of the latter implementations, the radius R_(O) cansatisfy the condition

R _(O) =R _(E)√[1+(n _(E) /n _(O))²].

In other cases of the latter implementations, the radius R_(O) cansatisfy the condition

R _(O) >R _(E)√[1+(n _(E) /n _(O))²].

In any of the above implementations, the lighting device further caninclude a reflector extending from the input interface to a boundary ofthe extraction interface.

In some implementations, the phosphor can be uniformly distributedwithin the dielectric material. In some implementations, the dielectricmaterial of the matrix can be plastic or glass. In some implementations,the one or more LEDs can include one or more LED dies. In someimplementations, the one or more LEDs can include one or more LEDpackages. In some implementations, the mixed light can include a portionof the converted light and a portion of the pump light that isunconverted by the phosphor.

The details of one or more implementations of the technologies describedherein are set forth in the accompanying drawings and the descriptionbelow. Other features, aspects, and advantages of the disclosedtechnologies will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a schematic diagram of a lighting device having alayer-shaped or 3D scattering element and an optical extractor with aconvex output surface.

FIG. 1B shows an example of a spectrum of mixed light output by alighting device like the one illustrated in FIG. 1A.

FIG. 2A shows a schematic cross section of an example of a lightingdevice having a spherical shell-shaped scattering element and aspherical shell-shaped optical extractor that have a common extractioninterface.

FIG. 2B shows a schematic cross section of an example of a lightingdevice having a plate-shaped scattering element and a sphericaldome-shaped optical extractor that have a common extraction interface.

FIG. 3 shows a schematic cross section of an example of a lightingdevice having a cylinder-shaped scattering element and a sphericaldome-shaped optical extractor that have a common extraction interface.

FIG. 4 shows a schematic cross section of an example of a lightingdevice having a spherical dome-shaped scattering element and a sphericalshell-shaped optical extractor that have a common extraction interface.

Reference numbers and designations in the various drawings indicateexemplary aspects, implementations of particular features of the presentdisclosure.

DETAILED DESCRIPTION

The present technology pertains to lighting devices including SSLdevices, layer-shaped or three-dimensional (3D) scattering elements, andoptical extractors with convex output surfaces. The disclosed lightingdevices can be used in applications such as general illumination, and/ordisplay illumination, e.g., projection displays, backlit LCDs, signage,etc.

FIG. 1A shows a schematic diagram of a lighting device 100 having alayer-shaped or 3D scattering element 120 and an optical extractor 130with a convex output surface 135. The lighting device 100 furtherincludes one or more light emitting elements (LEEs) 110 and aconversion/recovery enclosure 140. The lighting device 100 efficientlyprovides broadband, homogenized light to an ambient environment across abroad range of angles.

The LEEs are configured to produce and emit light during operation. Aspectral power distribution of light emitted by the LEEs 110 (alsoreferred to as pump light) can be concentrated in a blue wavelengthrange, for instance. Depending on the context, color of light may referto its chromaticity. In general, the LEEs 110 are devices that emitradiation in a region or combination of regions of the electromagneticspectrum for example, the visible region, infrared and/or ultravioletregion, when activated by applying a potential difference across it orpassing a current through it, for example. The LEEs 110 can havemonochromatic, quasi-monochromatic, polychromatic or broadband spectralemission characteristics. Examples of LEEs that are monochromatic orquasi-monochromatic include semiconductor, organic, polymer/polymericlight-emitting diodes (LEDs). In some implementations, the one or moreLEEs 110 can be a single specific device that emits the radiation, forexample an LED die, or/and can be a combination of multiple instances ofthe specific device that emit the radiation together. Such LEE(s) 110can include a housing or package within which the specific device ordevices are placed. As another example, the one or more LEEs 110 can bea single device that includes one or more lasers and more specificallysemiconductor lasers, such as vertical cavity surface emitting lasers(VCSELs) and edge emitting lasers. In embodiments utilizingsemiconductor lasers, the layer-shaped or 3D scattering element 120functions to reduce (e.g., eliminate) spatial and temporal coherence ofthe laser light, which may be advantageous where the lighting device 100may be viewed directly by a person. Further examples of LEEs 110 includesuperluminescent diodes and other superluminescent devices.

The layer-shaped or 3D scattering element 120 has an input surface 115positioned to receive the light from the LEEs 110. In some cases, theinput surface 115 is spaced apart from the one or more LEEs 110. Inother cases, the input surface 115 is an optical interface of the 3Dscattering element 120 with the one or more LEEs 110. In the lattercases, the input surface 115 will be referred to as the input interface115. The layer-shaped or 3D scattering element 120 includes scatteringcenters arranged to scatter the light from the LEEs 110 and to providemixed light. Such scattering may be configured to be substantiallyisotropical. The mixed light can include elastically scattered pumplight (represented as dashed-lines) and inelastically scattered pumplight (represented as dotted-lines). Depending on its nature, scatteringcan be the result of combined absorption/emission and/or refractiveinteraction with scattering centers. Elastically scattered pump light,if any, includes photons that have undergone elastic scattering at thescattering centers. Inelastically scattered pump light includes photonsthat have undergone inelastic scattering at the scattering centers. Forexample, the spectral distribution of photons remains substantiallyunchanged due to elastic scattering or, on the other hand, changes ineffect of inelastic scattering. Typical elastic scattering entailsrefraction of light at a scattering center, for example. Typicalinelastic scattering entails emission of light from a scattering centerin effect of light that was previously absorbed by the scatteringcenter.

With respect to the technology described in this specification,inelastic scattering typically is associated with one visible orultraviolet (UV) incoming photon and one visible outgoing photon.Scattering of light by a scattering center can result from effects suchas light conversion, refraction, and/or other effect and/or combinationthereof. The distribution of a plurality of outgoing photons that resultfrom inelastic scattering at one scattering center can be isotropic asis typically the case, for example, in effect of light conversion. Thedistribution of a plurality of outgoing photons that result from elasticscattering at multiple scattering centers can be isotropic depending on,for example, shapes, arrangements and/or compositions of the scatteringcenters. A scattering center can include one or more portions that eachscatter light in one or more ways, for example, by light conversion,refraction or other effect. Example scattering centers includediscontinuities in the composition or structure of matter. In order toachieve a predetermined degree of randomness in its propagation, lighthas to undergo multiple elastic scattering events. As such multiplescattering events are required to exceed a predetermined randomness, forexample, when the light is scattered by interaction with scatteringcenters that scatter light merely by refraction. Scattering centers caninclude light-converting material (LCM) and/or non-light convertingmaterial, for example. Light conversion via LCM is a form of inelasticscattering.

LCM is a material which absorbs photons according to a first spectraldistribution and emits photons according to a second spectraldistribution, as described below in connection with FIG. 1B. The termslight conversion, wavelength conversion and/or color conversion are usedinterchangeably. LCM is also referred to as photoluminescent orcolor-converting material, for example. LCM can include photoluminescentsubstances, fluorescent substances, phosphors, quantum dots,semiconductor-based optical converters, or the like. LCM also caninclude rare earth elements.

FIG. 1B shows an example of a spectrum 115 of mixed light that is outputby the lighting device 100. A blue LED used as LEE 110 in the lightingdevice 100 can have an emission spectrum 111. In addition, FIG. 1B showsan absorption spectrum 112 and an emission spectrum 113 of thescattering centers, along with the spectrum of mixed light 115 (thelatter is represented with a dotted-line.) Spectral power distributionof the elastically scattered light is the same as the spectral powerdistribution of the pump light (corresponding to the spectrum 111.)Moreover, the absorption spectrum of the scattering centers 112 overlapsthe spectrum of the light emitted by the light-emitting element 111.Spectral power distribution of the inelastically scattered light isdifferent from the pump light. For instance, inelastically scatteredlight will have a spectrum 113 that is shifted (e.g., Stokes shifted) tolonger wavelengths than the pump light spectrum 111. For example, bluepump light, when inelastically scattered, can yield light with anoverall yellow/amber color, e.g., corresponding to the spectrum 113.Moreover, the spectrum of mixed light 115 is a combination of thespectrum 111 of the elastically scattered light and spectrum 113 of theinelastically scattered light.

Referring again to FIG. 1A, the layer-shaped or 3D scattering element120 can be configured to substantially randomize the direction ofpropagation of light received from LEEs 110 by scattering substantiallyall light entering the layer-shaped or 3D scattering element, whileallowing substantial portions of light to pass through the layer-shapedor 3D scattering element.

The optical extractor 130 is formed from a transparent material, such asa transparent glass or a transparent organic polymer, and has a convexoutput surface 135. The output surface 135 is generally a transparentsurface. In other words, changes in the mixed light passing through theoutput surface 135 can generally be described by Snell's law ofrefraction, as opposed to, for example, an opaque or diffuse surfacewhere further scattering of transmitted light occurs. The opticalextractor 130 is in contact with the layer-shaped or 3D scatteringelement 120, such that there is an optical interface 125 between thelayer-shaped or 3D scattering element and the optical extractor at theplace of contact, and the optical interface is opposite the inputsurface/interface 115 of the layer-shaped or 3D scattering element. Theoptical interface 125 is referred to as the extraction interface 125.The layer-shaped or 3D extractor element 130 is arranged so that mixedlight transmitted through the extraction interface 125 enters theoptical extractor 130. Light from the layer-shaped or 3D scatteringelement 120 that directly reaches the output surface 135 of the opticalextractor 130 is referred to as forward light.

In some implementations, the lighting device 100 includes a medium, suchas a gas (e.g., air), between the LEEs 110 and the input surface 115 ofthe layer-shaped or 3D scattering element 120 having a refractive indexn₀, and the layer-shaped or 3D scattering element includes a materialhaving a first refractive index n_(S), where n₀<n_(S). Light from thelayer-shaped or 3D scattering element 120 that reaches the input surface115 is referred to as backward light. Because n₀<n_(S), the inputsurface 115 allows only a fraction of the backward light to escape intothe low-index medium. Here, the transparent material of the opticalextractor 130 has a refractive index n_(E), where n₀≤n_(E) and isimmersion-coupled with the extraction interface 125. As such, thelighting device 100 asymmetrically propagates mixed light because theamount of transmitted forward light is greater than the amount ofbackward light transmitted into the low index medium. In such a case,depending on the degree of asymmetry between n₀ and n_(E), theextraction interface 125 between the layer-shaped or 3D scatteringelement 120 and the optical extractor 130 permits varying ratios offorward to backward light transmission. A high asymmetry in this ratiois reached if n_(E) and n_(S) are about equal. Light emitting devicesthat feature asymmetric optical interfaces (i.e., different refractiveindex mismatches) on opposing sides of the layer-shaped or 3D scatteringelement 120 are referred to as asymmetric scattering light valves(ASLV), or ASLV lighting devices.

The output surface 135 of the optical extractor 130 is a transparentsurface that is shaped such that the mixed light that directly impingeson the output surface satisfies specified reflection conditions toensure that the mixed light that directly impinges on the output surfaceexperiences little or no total internal reflection (TIR). In thismanner, the output surface 135 transmits a large portion of lightimpinging thereon that directly propagates thereto from the layer-shapedor 3D scattering element 120 and propagates in at least certain planesand outputs it into the ambient of the optical extractor 130 on firstpass. The mixed light output through the output surface 135 can be usedfor illumination or indication functions provided by the lighting device100 or for further manipulation by another optical system that works inconjunction with the lighting device.

Some of the specified reflection conditions satisfied by the shape ofthe output surface 135 of the optical extractor 130 are described below.In some embodiments, the output surface 135 of the optical extractor 130is shaped as a spherical or a cylindrical dome or shell with a radiusR_(O), such that the extraction interface 125 is disposed within an areaof the optical extractor defined by a respective notional sphere orcylinder that is concentric with the output surface and has a radiusR_(W)=R_(O)/n_(E), wherein n_(E) is the refractive index of the opticalextractor. Such a configuration is referred to as Weierstrass geometryor Weierstrass configuration. It is noted that a spherical Weierstrassgeometry can avoid TIR for rays passing through the area circumscribedby a corresponding notional R_(O)/n_(E) sphere irrespective of the planeof propagation. A cylindrical Weierstrass geometry can exhibit TIR forlight that propagates in planes that intersect the respective cylinderaxis at shallow angles even if the light passes through an areacircumscribed by a corresponding notional R_(W)=R_(O)/n_(E) cylinder.

It is noted that other lighting devices can have an extractor element130 with non-spherical or non-cylindrical output surface 135 the can beemployed to refract light and aid in shaping an output intensitydistribution in ways different from those provided by a spherical orcylindrical exit surface. The definition of the Weierstrass geometry canbe extended to include an output surface 135 with non-circular sectionsby requiring that the extraction interface 125 falls within cones, alsoreferred to as acceptance cones, subtended from points P of the outputsurface whose axes correspond to respective surface normals at thepoints P and which have an apex of 2*Arcsin(k*n_(O)/n_(E)), whereinn_(O) is the refractive index of the medium on the outside of the outputsurface and k is a positive number smaller than n_(E). It is noted thatthe output surface 135 needs to be configured such that the plurality ofall noted cones circumscribe a space with a non-zero volume. It isfurther noted that k is assumed to refer to a parameter that determinesthe amount of TIR at an uncoated output surface 135 that separates anoptically dense medium, having n_(E)>1, on one side of the outputsurface making up the optical extractor 130 from a typical gas such asair with n_(O)˜1.00 at standard temperature and pressure conditions, onthe outside of the output surface. Depending on the embodiment, k can beslightly larger than 1 but is preferably less than 1. If k>1, some TIRmay occur at the output surface 135 inside the optical extractor 130. Insome embodiments, this results in the extraction interface 125 being atleast R(P)*(1−k/n_(E)) away from the output surface 135 in a directionnormal to the output surface at a point P thereof. Here, R(P) is thelocal radius of curvature of the output surface 135 at the point P, andn_(E) is the refractive index of the optical extractor 130. For aspherical or cylindrical output surface 135 with k=1, the boundariescircumscribed by the noted cones correspond to a spherical orcylindrical Weierstrass geometry, respectively. In this case, the mixedlight received by the optical extractor 130 through the extractioninterface 125 impinges on the output surface 135 at incident anglessmaller than the critical angle θ_(C)=arcsin(n_(E)). Some embodimentsare configured to allow for some TIR by choosing k>1. In such cases, k/nis limited to k/n<0.8, for example. In summary, a lighting device 100 issaid to satisfy the Weierstrass configuration if a radius R_(O) of theoutput surface 135 of the optical extractor 130, which has an index ofrefraction n_(E), is equal to or larger than R_(O)≥R_(W)=n_(E)R_(E),where R_(E) is a radius of the extraction interface 125 of the lightingdevice.

In some embodiments, the parameter k is not just smaller than 1 to avoidTIR at the output surface 135 of the optical extractor 130 for lightpropagating in at least one plane, but k is made so small that certainFresnel reflections are additionally avoided. In such cases, the mixedlight received by the optical extractor 130 through the extractioninterface 125 impinges on the output surface 135 at incident anglesequal to or smaller than the Brewster angle θ_(B)=arctan(n_(E)) againstan air interface. More generally, p-polarized light that impinges at apoint P of the output surface 135 from within directions bound by a conesubtended from the point P with apex 2*Arctan(1/n_(E)) whose axiscorresponds to the surface normal at the point P will not be reflectedat the exit surface. Such a configuration is referred to as Brewstergeometry (or Brewster configuration), and the output surface 135 forms aBrewster sphere or a Brewster cylinder. In summary, a lighting device100 is said to satisfy the Brewster configuration if a radius R_(O) ofthe output surface 135 of the optical extractor 130 is equal to orlarger than R_(O)≥R_(B)=R_(E)(1+n_(E) ²)^(+1/2), where R_(E) is theradius of the extraction interface 125 of the lighting device. Note thatfor a given radius R_(E) of the extraction interface 125 of the lightingdevice 100, an optical extractor 130 that satisfies the Brewstercondition has an output surface 135 with minimum radiusR_(O)(Brewster;min)=R_(B) that is larger than a minimum radius R_(O)(Weierstrass;min)=R_(W) of the output surface of an optical extractorthat satisfies the Weierstrass condition.

In a first implementation of the optical extractor 130, the radius R_(O)of its output surface 135 is larger than or equal to the Brewsterradius: R_(O)≥R_(B)=R_(E) (1+n_(E) ²)^(+1/2), for a given radius R_(E)of the extraction interface 125. A volume V_(E) of the optical extractor130 in the first implementations can vary from a minimum volume equal toa Brewster volume, V_(E)=V_(B) for R_(O)=R_(B), to infinity, V_(E)→∞ forR_(O)→∞. The losses suffered by the mixed light due to Fresnelreflections at the output surface 135 (of an optical extractor 130having a refraction index n_(E)=1.5) increase by only about 20% when thevolume V_(E) of the optical extractor 130 decreases from ∞ to theBrewster volume V_(B).

In some other implementations of the optical extractor 130, the radiusR_(O) of its output surface 135 is between the Weierstrass radiusR_(W)=n_(E)R_(E), for a given radius R_(E) of the extraction interface125, and the Brewster radius: R_(W)≤R_(O)<R_(B). The volume V_(E) of theoptical extractor 130 in the second implementations can vary from aminimum volume equal to a Weierstrass volume, V_(E)=V_(W) forR_(O)=R_(W), to a maximum volume equal to the Brewster volume,V_(E)=V_(B) for R_(O)=R_(B). The losses suffered by the mixed light dueto Fresnel reflections at the output surface 135 (of an opticalextractor 130 having a refraction index n_(E)=1.5) increase by 50% whilethe volume of the optical extractor 130 decreases by only 20% from theBrewster volume V_(B) to the Weierstrass volume V_(W). In view of theforegoing volume to loss penalty considerations for the first and secondimplementations, some embodiments of the optical extractor 130 will havea radius of its output surface 135 that satisfies the conditionR_(O)≈1.5R_(B), 1.2R_(B), 1.1R_(B), R_(B), 0.9R_(B), 0.8R_(B), or0.5R_(B), for instance. The above estimates of the loss penalty for theoptical extractor 130 as a function of its volume are described indetail in the Annex of provisional application 62/084,358 (which isincorporated by reference herein), in connection with FIG. 2B.

Further in the example shown in FIG. 1A, the conversion/recoveryenclosure 140 is defined to enclose the layer-shaped or 3D scatteringelement 120. The conversion/recovery enclosure 140 is arranged andconfigured to recover a portion of the mixed light that propagates inthe backward direction by causing at least some of this mixed light toexit the layer-shaped or 3D scattering element 120 through theextraction interface 125 into the optical extractor 130, and reducingthe amount of mixed light that returns to the LEEs 110 (where it can beabsorbed). If a 3D scattering element 120 fully fills theconversion/recovery enclosure 140 as shown in FIGS. 3 and 4, then theconversion/recovery enclosure represents simply a conversion enclosurethat is “bound” by the input interface 115, the extraction interface 125of the 3D scattering element and one or more additional opticalcomponents that redirect back-scattered light away from the inputinterface. If a layer-shaped scattering element 120 does not fully fillthe conversion/recovery enclosure 140 as shown in FIGS. 2A and 2B, thenthe conversion/recovery enclosure also encloses a medium adjacent theinput surface 115 of the layer-shaped scattering element. In one suchexample illustrated in FIG. 2A, the conversion/recovery enclosure 240 ais bound by the extraction interface 225 a and a reflector 245 a. Inanother such example illustrated in FIG. 2B, the conversion/recoveryenclosure 240 b is bound by the extraction interface 225 b and sidesurfaces 245 b of an optical coupler 245 b. Referring again to FIG. 1A,note that the backscattered light recovered from the conversion/recoveryenclosure 140 further increases asymmetry in the propagation of lightthrough the lighting device 100.

Moreover, the lighting device 100 can be fabricated using conventionalextrusion and molding techniques and conventional or other assemblytechniques—some examples are described herein. Components of thelighting device 100 can include one or more organic or inorganicmaterials, for example acrylic, silicone, polypropylene (PP),polyethylene terephthalate (PET), polycarbonate, polyvinylidene fluoridesuch as Kynar™, lacquer, acrylic, rubber, polyphenylene sulfide (PPS)such as Ryton™, polysulfone, polyetherimide (PEI), polyetheretherketone(PEEK), polyphenylene oxide (PPO) such as Noryl™, glass, quartz,silicate, adhesive, other polymers organic or inorganic glasses and/orother materials.

In some embodiments, the optical extractor 130 and the layer-shaped or3D scattering element 120 are integrally formed. In an example of suchan integral formation, the extraction interface 125 is a notionalinterface drawn between regions of a corresponding integrally formedobject, such that the extraction interface substantially includesinterfaces formed by the scattering centers. This may be the case, whenthe layer-shaped or 3D scattering element 120 includes scatteringcenters inside a material that is the same as the material used to formthe optical extractor 130, for example. In this manner, the layer-shapedor 3D scattering element 120 can be shaped as a tile, disc, spherical oraspherical shell or dome, tubular, prismatic or other elongate shell, orother structure to provide a predetermined spatial profile of conversionproperties to achieve a predetermined light-output profile includingcolor and/or brightness homogeneity from the layer-shaped or 3Dscattering element.

The layer-shaped or 3D scattering element 120 can be adjacent to, orpartially or fully surrounded by, the optical extractor 130. Variousshapes of the layer-shaped or 3D scattering element 120 and of theoptical extractor 130, and their combinations, are described in detailbelow in connection with FIGS. 2A, 2B, 3 and 4.

FIG. 2A shows a schematic cross section in the x-z plane of a lightingdevice 200 a having a spherical shell-shaped scattering element 220 aand a spherical shell-shaped optical extractor 230 a that have a commonextraction interface 225 a. In some implementations, the lighting device200 a has rotational symmetry around the z-axis. In otherimplementations, the lighting device 200 a is elongated along the y-axis(i.e., along a direction perpendicular to the page). The lighting device200 a further includes one or more LEEs 210 (e.g., a blue pump), and aflat reflector 245 a (e.g., a mirror represented by a double line.) Thescattering element 220 a has an input surface 215 a spaced apart fromthe LEEs 210 and positioned to receive the light from the LEEs. In thisexample, an LEE 210 is inserted into an opening (e.g., having ahalf-width R_(d)) of the flat reflector 245 a. A dimension 2R_(d) in thex-y plane of the LEE 210 can be of order 1 mm, for instance. In someimplementations, the reflector 245 a extends to at least the inputsurface 215 a of the scattering element 220 a. In other implementations,the reflector 245 a extends to at least an output surface 235 of theoptical extractor 230 a. In this example, the spherical shell-shapedscattering element 220 a is located on the inside of the opticalextractor 230 a and has substantially uniform thickness, such that adistance between the extraction interface 225 a and the input surface215 a of the scattering element is constant for any point of the opticalextraction. The thickness of the spherical shell-shaped scatteringelement 220 a is less than 1 mm, e.g., 0.5, 0.2, 0.1 mm, or otherthicknesses. Note that, in this example, the thickness of the sphericalshell-shaped scattering element 220 a is about 3×-10× smaller than thedimension 2R_(d) of the LEE 210. As such, the spherical shell-shapedscattering element 220 a is first embodiment of the layer-shapedscattering element 120 described above in connection with FIG. 1A.

Moreover, the input surface 215 a of the spherical shell-shapedscattering element 220 a is adjacent an air filled semisphericalenclosure 240 a of the optical extractor 230 a. The enclosure 240 aencompasses the LEE 210 and its surrounding reflector 245 a. Here, aradius R_(E) of the extraction interface 225 a can be of order 3-5 mm.In some implementations, the output surface 235 of the extractor element230 a is concentric with the extraction interface 225 a and has a radiusR_(O) that satisfies one of the following reflection conditions.Reflection condition 1: R_(O)>R_(B), where the Brewster radius R_(B) isrelated to the radius R_(E) of the extraction interface 225 a throughR_(B)=R_(E)(1+n_(E) ²)^(+1/2); Reflection condition 2: R_(O)=R_(B);Reflection condition 3: R_(W)<R_(O)<R_(B), where the Weierstrass radiusR_(W) is related to the radius R_(E) of the extraction interface throughR_(W)=n_(E)R_(E); Reflection condition 4: R_(O)=R_(W). In this manner,mixed light that directly impinges on the output surface 235 experienceslittle or no total internal reflection thereon.

Further in this example, light propagation asymmetry in large partarises from the refraction indices of materials on the inside (index n₀)and outside (index n_(E)) of the spherical shell-shaped scatteringelement 220 a (with index n_(S)) being unequal. For instance, if1.3<n_(S)<1.6 and n₀=1.0, that is n₀<n_(S), a large fraction (˜75%) ofthe isotropically distributed mixed light impinging on the input surface215 a will be reflected by TIR back into the spherical shell-shapedscattering element 220 a and only a smaller fraction (˜25%) will betransmitted backwards into the air medium of the recovery enclosure 240a from where some may reach the LEE 210. In some implementations, at theextraction interface 225 a, the condition n_(S)≤n_(E) will guaranteethat substantially all the mixed light reaching the extraction interfacewill transition into the extractor element 230 a, and either of theabove-noted reflection conditions 1, 2, 3 or 4 will further guaranteethat practically all the mixed light will transmit into air without TIRthrough the output surface 235. Only a small fraction (down to about ˜4%depending on incidence angle) will be returned by Fresnel reflection atthe output surface 235.

FIG. 2B shows a schematic cross section of an example of a lightingdevice 200 b having a plate-shaped scattering element 220 b and aspherical dome-shaped optical extractor 230 b that have a commonextraction interface 225 b. In some implementations, the lighting device200 b has rotational symmetry around the z-axis. In otherimplementations, the lighting device 200 b is elongated along the y-axis(i.e., along a direction perpendicular to the page). The lighting device200 b further includes one or more LEEs 210 (e.g., a blue pump), and anoptical coupler 245 b (e.g., configured as a compound paraboliccollector (CPC), a conical or other hollow optical coupler havingreflective side surfaces represented by double lines.) Note that an airfilled enclosure 240 b of the optical coupler 245 b encompasses an LEE210 and the plate-shaped scattering element 220 b. Here, the LEE 210 ispositioned at an input aperture of the optical coupler 245 b. Adimension 2R_(d) in the x-y plane of the LEE 210 can be of order 1 mm,for instance. The plate-shaped scattering element 220 b is positioned atan output aperture of the optical coupler 245 b and has an input surface215 b through which it receives the pump light from the LEE 210. In thisexample, the plate-shaped scattering element 220 b has substantiallyuniform thickness, such that a distance between the extraction interface225 b and the input surface 215 b of the plate-shaped scattering elementis constant for any point of the optical extraction. The thickness ofthe plate-shaped scattering element 220 b is less than 1 mm, e.g., 0.5,0.2, 0.1 mm, or other thicknesses. Note that, in this example, thethickness of the plate-shaped scattering element 220 b is about 3×-10×smaller than the dimension 2R_(d) of the LEE 210. Additionally, adimension 2R_(E) in the x-y plane of the scattering element 220 b can beof order 3-5 mm. As such, the plate-shaped scattering element 220 b is asecond embodiment of the layer-shaped scattering element 120 describedabove in connection with FIG. 1A.

Note that the extraction interface 225 b is inscribed in (i.e., forms achord of) a nominal sphere (represented in dashed-line) that isconcentric with the output surface 235 of the optical extractor 230 b.The largest such nominal sphere has a diameter equal to the dimension2R_(E) in the plane x-y of the extraction interface 225 b. In thecurrent disclosure, a radius R_(O) of the output surface 235 satisfiesone of the following reflection conditions. Reflection condition 1:R_(O)>R_(B), where the Brewster radius R_(B) is related to the dimension2R_(E) of the extraction interface 225 b through R_(B)=R_(E)(1+n_(E)²)^(+1/2); Reflection condition 2: R_(O)=R_(B); Reflection condition 3:R_(W)<R_(O)<R_(B), where the Weierstrass radius R_(W) is related to thedimension 2R_(E) of the extraction interface through R_(W)=n_(E)R_(E);Reflection condition 4: R_(O)=R_(W). In this manner, mixed light thatdirectly impinges on the output surface 235 experiences little or nototal internal reflection thereon.

Further in this example, light propagation asymmetry arises mostly fromthe refraction indices of materials on the inside (index n₀) and outside(index n_(E)) of the plate-shaped scattering element 220 b (with indexn_(S)) being unequal. For instance, if 1.3<n_(S)<1.6 and n₀=1.0, that isn₀<n_(S), a large fraction (˜75%) of the isotropically distributed mixedlight impinging on the input surface 215 b will be reflected by TIR backinto the plate-shaped scattering element 220 b and only a smallerfraction (˜25%) will be transmitted backwards into the air medium of therecovery enclosure 240 b from where some may reach the LEE 210. In someimplementations, at the extraction interface 225 b, the conditionn_(S)≤n_(E) will guarantee that substantially all the mixed lightreaching the extraction interface will transition into the opticalextractor 230 b, and either of the above-noted reflection conditions 1,2, 3 or 4 will further guarantee that practically all the mixed lightwill transmit into air without TIR through the output surface 235. Onlya small fraction (down to about ˜4% depending on incidence angle) willbe returned by Fresnel reflection at the output surface 235.

As noted above, the lighting device 200 a has a spherical shell-shapedscattering element 220 a and the lighting device 200 b has aplate-shaped scattering element 220 b, each of these layer-shapedscattering elements can have a thickness comparable to a characteristicdimension of the LEEs 210. The lighting devices described below have 3Dscattering elements with a thickness that can be a few to many times acharacteristic dimension of the LEEs.

For example, FIG. 3 shows a schematic cross section of a lighting device300 having a thick, for example cylinder-shaped, scattering element 320and a spherical dome-shaped optical extractor 230 b that have a commonextraction interface 225 b. The cylinder-shaped scattering element 320is an example embodiment of the 3D scattering element 120 describedabove in connection with FIG. 1A. As another example, FIG. 4 shows aschematic cross section of an example of a lighting device 400 having aspherical dome-shaped scattering element 420 and a sphericalshell-shaped optical extractor 230 a that have a common extractioninterface 225 a. The spherical dome-shaped scattering element 420 isanother embodiment of the 3D scattering element 120 described above inconnection with FIG. 1A. In some implementations, the lighting device300/400 has rotational symmetry around the z-axis. In otherimplementations, the lighting device 300/400 is elongated along they-axis (i.e., along a direction perpendicular to the page).

The lighting device 300/400 further includes one or more LEEs 210. Asdescribed above in connection with FIG. 1A, the LEE(s) 210 can includelight emitting diodes (LEDs). For example, the LEDs can emit pump light,as described above in connection with FIG. 1B. In some cases, the LEDscan be bare LED dies. In some other cases, the LEDs can be packaged LEDdies. In the latter cases, the packaged LED dies can include a lens orother light shaping optical element.

The 3D scattering element 320/420 can include a matrix of phosphorparticles embedded in dielectric material. The phosphor can absorb aportion of the pump light and emit converted light with converted lightwavelengths longer than pump light wavelengths, as illustrated in FIG.1B, for instance. Here, the dielectric material is transparent to thepump light and the converted light. In this manner, the 3D scatteringelement 320/420 provides mixed light which includes a portion of theconverted light and a portion of the pump light that is not absorbed bythe phosphor, as illustrated in FIG. 1B, for instance. In someimplementations, the dielectric material of the matrix is plastic. Inother implementations, the dielectric material of the matrix is glass.Moreover, the phosphor particles can be uniformly distributed in thedielectric material. In this manner, an effective refracting index ofthe 3D scattering element 320/420 is n_(S)>1, e.g., 1.3<n_(S)<1.6.

The optical extractor 230 b/230 a can include a material that istransparent to the mixed light and has a refractive index n_(E) that islarger than a refraction index n_(O) of an environment surrounding theoptical extractor. The material of the optical extractor 230 b/230 a canbe plastic or glass. A value of the refractive index n_(E) of theoptical extractor material is in the range of 1.3<n_(E)<1.9, forinstance. In some implementations, n_(E) can be smaller than n_(S). Inother implementations, n_(E) can be equal to or larger than n_(S).

Further, the 3D scattering element 320/420 can form an immersion-coupledinput interface 315 with the LEE(s) 210, such that the pump lightemitted by the LEE(s) is input into the 3D scattering element throughthe input interface. Furthermore, the optical extractor 230 b/230 aforms an immersion-coupled extraction interface 225 b/225 a with the 3Dscattering element 320/420, such that the mixed light is input into theoptical extractor from the 3D scattering element through the extractioninterface. Moreover, an output surface 235 of the optical extractor 230b/230 a is arranged and shaped relative to the extraction interface 225b/225 a such that the mixed light received by the optical extractorthrough the extraction interface impinges on the output surface atincident angles smaller than a predetermined angle. Examples ofpredetermined angles corresponding to particular reflection conditionsare provided below in this specification.

The lighting device 300/400 further includes a reflector 345/245 a(represented in FIGS. 3 and 4 by double lines) extending from the inputinterface 315 to a boundary of the extraction interface 225 b/225 a. Inthis manner, a cylinder-shaped conversion chamber (corresponding to theconversion enclosure 140 of the lighting device 100 shown in FIG. 1A) ofthe lighting device 300 shown in FIG. 3 is bounded by the reflector 345and the extraction interface 225 b and encloses the cylinder-shapedscattering element 320. Further, a spherical dome-shaped conversionchamber (taking the position of the conversion enclosure 140 of thelighting device 100 shown in FIG. 1A) of the lighting device 400 shownin FIG. 4 is bounded by the reflector 245 a and the extraction interface225 a and encloses the spherical dome-shaped scattering element 420. Insome implementations, the reflector 245 a can extend along the x-axisbeyond the boundary of the extraction interface 225 a at least to theboundary of the output surface 235. The reflector 345/245 a can beconfigured to reflect the mixed light via specular reflection or diffusereflection. A reflectivity of the reflector 345/245 a is larger than90%, e.g., 95%, 99%, etc. In some implementations the reflectors 345/245a provide a white diffuse reflective surface, which, when immersioncoupled with the scattering element 320/420, can provide very highreflectivity.

Moreover, the input interface 315 has a first dimension, 2R_(d). In theexamples illustrated in FIGS. 3 and 4, the first dimension 2R_(d) is inthe x-y plane and can represent a length of the LED die or LED packagethat forms the LEE 210. The first dimension 2R_(d) is of order 1 mm, forinstance.

Referring now to FIG. 3, the cylinder-shaped scattering element 320 hasa second dimension, T, which is orthogonal to and 1-10 times larger thanthe first dimension 2R_(d) of the input interface 315. Here, the seconddimension T represents a thickness along the z-axis of thecylinder-shaped scattering element 320. Additionally, thecylinder-shaped scattering element 320 has a third dimension, 2R_(E),which is along and 3-30 times larger than the first dimension 2R_(d) ofthe input interface 315. Here, the third dimension 2R_(E) represents alength in the x-y plane of the cylinder-shaped scattering element 320.In this example, the extraction interface 225 b also has the thirddimension 2R_(E) in the x-y plane.

In this example, the extraction interface 225 b is inscribed in (i.e.,forms a chord of) a nominal sphere (represented in dashed-line) that isconcentric with the output surface 235 of the spherical dome-shapedoptical extractor 230 b. The largest such nominal sphere has a diameterequal to the third dimension 2R_(E) in the plane x-y of the extractioninterface 225 b. In the current disclosure, a radius R_(O) of the outputsurface 235 satisfies one of the following reflection conditions.Reflection condition 1: R_(O)>R_(B), where the Brewster radius R_(B) isrelated to the third dimension 2R_(E) of the extraction interface 225 bthrough R_(B)=R_(E)(1+n_(E) ²)^(+1/2); Reflection condition 2:R_(O)=R_(B); Reflection condition 3: R_(W)<R_(O)<R_(B), where theWeierstrass radius R_(W) is related to the third dimension 2R_(E) of theextraction interface through R_(W)=n_(E)R_(E); Reflection condition 4:R_(O)=R_(W). In this manner, mixed light that directly impinges on theoutput surface 235 of the spherical dome-shaped optical extractor 230 bexperiences little or no total internal reflection thereon for thefollowing reasons. For all reflection conditions 1-4, the mixed lightdirectly impinges on the output surface 235 at incidence angles smallerthan or equal to the critical angle θ_(C)=arcsin(n_(E)/n_(O)). Moreover,for conditions 1-2, the mixed light directly impinges on the outputsurface 235 at incidence angles smaller than or equal to the Brewsterangle θ_(B)=arctan(n_(E)/n_(O)).

Referring now to FIG. 4, the scattering element 420 can be a dome-shapedhemi-sphere. Here, the dome-shaped scattering element 420 has a seconddimension, R_(E), which is radial with respect to the input interface315 and 1-10 times larger than the first dimension 2R_(d) of the inputinterface. Here, the second dimension R_(E) represents a radius of theextraction interface 225 a. Additionally, the spherical dome-shapedscattering element 420 has a third dimension which coincides with alength of the extraction interface 225 a. Here, the length of theextraction interface 225 a is ˜πR_(E), e.g., 3-30 times larger than thefirst dimension 2R_(d) of the input interface 315.

In some implementations, the output surface 235 of the sphericalshell-shaped optical extractor 230 a is concentric with the extractioninterface 225 a and has a radius R_(O) that satisfies one of thefollowing reflection conditions. Reflection condition 1: R_(O)>R_(B),where the Brewster radius R_(B) is related to the radius R_(E) of theextraction interface 225 a through R_(B)=R_(E)(1+n_(E) ²)^(+1/2);Reflection condition 2: R_(O)=R_(B); Reflection condition 3:R_(W)<R_(O)<R_(B), where the Weierstrass radius R_(W) is related to theradius R_(E) of the extraction interface through R_(W)=n_(E)R_(E);Reflection condition 4: R_(O)=R_(W). In this manner, mixed light thatdirectly impinges on the output surface 235 of the sphericalshell-shaped optical extractor 230 a experiences little or no totalinternal reflection thereon for the following reasons. For allreflection conditions 1-4, the mixed light directly impinges on theoutput surface 235 at incidence angles smaller than or equal to thecritical angle θ_(C)=arcsin(n_(E)/n_(O)). Moreover, for conditions 1-2,the mixed light directly impinges on the output surface 235 at incidenceangles smaller than or equal to the Brewster angleθ_(B)=arctan(n_(E)/n_(O)).

Note that, in contrast with the lighting device 300 having acylinder-shaped scattering element 320 with a thickness T (orthogonal tothe input interface 315) that is larger than the dimension 2R_(d) of itsLEE 210, e.g., T=1-10×2R_(d), the corresponding lighting device 200 bhas a plate-shaped scattering element 220 b with a thickness thatrepresents a fraction of the dimension R_(d) of its LEE 210, e.g.,˜0.5-0.1×2R_(d). Similarly, in contrast with the lighting device 400having a spherical dome-shaped scattering element 420 with a radiusR_(E) that is larger than the dimension 2R_(d) of its LEE 210, e.g.,R_(E)=1-10×2R_(d), the corresponding lighting device 200 a has aspherical shell-shaped scattering element 220 a with a thickness thatrepresents a fraction of the dimension R_(d) of its LEE 210, e.g.,˜0.5-0.1×2R_(d). While the 3D scattering element 320/420 of the lightingdevice 300/400 and the layer-shaped scattering element 220 b/220 a ofthe corresponding lighting device 200 b/200 a may contain similarquantities of phosphor, a volume of the former can be much larger than avolume of the latter. Hence, the phosphor in the 3D scattering element320/420 of the lighting device 300/400 can be more dilute than thephosphor in the layer-shaped scattering element 220 b/220 a of thecorresponding lighting device 200 b/200 a. Likewise, the mean free pathlengths can be longer. In this manner, a likelihood for the convertedlight to backscatter towards the input interface 315 for the lightingdevice 300/400 is beneficially smaller than a likelihood for theconverted light to backscatter towards the input interface 215 b/215 afor the corresponding lighting device 200 b/200 a. As such, in the caseof the lighting device 300/400, a remaining portion of the backscatteredlight is reflected off the reflector 345/245 a (which has a higherreflectance than a surface of an LEE 210—that is the input interface 315as viewed from the 3D scattering element 320/420.) Additionally, alikelihood for the converted light—that scatters laterally (e.g., in thex-y plane) relative to a forward direction (e.g., along the z-axis)between the input interface 315 and the extraction interface 225 b/225a—to be absorbed for the lighting device 300/400 is beneficially smallerthan a likelihood for the converted light—that scatters laterally (e.g.,in the tangential direction/x-y plane) relative to a forward direction(e.g., along the radial direction/z-axis) between the input interface215 b/215 a and the extraction interface 225 b/225 a—to be absorbed forthe corresponding lighting device 200 b/200 a. In this manner, in thecase of the lighting device 300/400, a remaining portion of thelaterally scattered converted light is reflected off the reflector345/245 a. Additionally, larger mean free path lengths in the 3Dscattering element 320/420 than in the corresponding layer-shapedscattering element 220 b/220 a allow for better spreading of lightacross the extraction interface 225 b/225 a. This can provide greateruniformity in brightness and/or color, for example.

As such, contributions to increasing the efficiency of the lightingdevice 300/400 over the corresponding lighting device 200 b/200 a comefrom an effective conversion cavity enclosing the 3D scattering element320/420. Depending on the embodiment, the thickness of the scatteringelement may be half to twice the mean free path length and about one toten times the first dimension of the input interface. The foregoingembodiments of the technology can be varied in many ways. Such presentor future variations are not to be regarded as a departure from thespirit and scope of the technology, and all such modifications as wouldbe obvious to one skilled in the art are intended to be included withinthe scope of the following claims.

The preceding figures and accompanying description illustrate examplemethods, systems and devices for illumination. It will be understoodthat these methods, systems, and devices are for illustration purposesonly and that the described or similar techniques may be performed atany appropriate time, including concurrently, individually, or incombination. In addition, many of the steps in these processes may takeplace simultaneously, concurrently, and/or in different orders than asshown. Moreover, the described methods/devices may use additionalsteps/parts, fewer steps/parts, and/or different steps/parts, as long asthe methods/devices remain appropriate.

In other words, although this disclosure has been described in terms ofcertain aspects or implementations and generally associated methods,alterations and permutations of these aspects or implementations will beapparent to those skilled in the art. Accordingly, the above descriptionof example implementations does not define or constrain this disclosure.Further implementations are described in the following claims.

1-24. (canceled)
 25. A lighting device comprising: a light-emittingelement (LEE) configured to provide light; a conversion element formingan input interface at points of contact with the LEE, the inputinterface having a first dimension, the scattering element having asecond dimension being orthogonal to the first dimension, the seconddimension being 1-10 times the size of the first dimension, theconversion element comprising a phosphor and a transparent material, thephosphor configured to convert received light into converted light, theconversion element having an outer surface configured to output at leasta portion of light received from the conversion element.
 26. Thelighting device of claim 25 further comprising a transparent extractorin contact with the outer surface of the conversion element.